1. Field of the Invention
The present invention relates to a drive device and an image forming apparatus, and especially relates to a drive device including a clutch, and an image forming apparatus in which the drive device is mounted.
2. Description of the Related Art
There is a drive device including a clutch that connects/disconnects rotation of a motor as a drive source to a driven member. For example, the drive device is mounted in an image forming apparatus such as a multi-functional peripheral (MFP). In the image forming apparatus, the drive device for driving a conveyance roller is used when print sheets are conveyed from a cassette or a sheet feeding tray to a development position one by one.
That is, a pushing-up plate for raising the stored sheets to a position where an upper surface of a bundle of sheets abuts on a sheet feeding roller installed at an upper side is installed in the cassette or the sheet feeding tray. The pushing-up plate is positioned on a bottom surface of the cassette or the sheet feeding tray so that the sheets can be supplied at a normal time other than the time of feeding the sheets. At the time of feeding the sheets, the drive device pushes up the pushing-up plate to raise the sheets stored therein, and allows the upper surface of the sheets comes in contact with the sheet feeding roller. When conveyance is terminated, the drive device lowers the pushing-up plate to put it to the original position.
To perform the operation, it is necessary to grasp the position of the pushing-up plate at the time of starting the operation. That is, the drive device needs to set the driven member to an initial position (home position) of the operation after accurately grasping the position of the driven member at the time of starting driving. In the case where the driven member is the pushing-up plate, it is necessary to position the pushing-up plate on the bottom surface of the cassette or the sheet feeding tray at the time of starting the sheet feeding operation.
The position of the driven member such as the pushing-up plate can be detected using a sensor or the like. For example, JP 2005-335859A disclose technologies that detect the position of a pushing-up plate by detecting the position of a member that transmits drive force to the pushing-up plate using a sensor.
However, meanwhile, there are needs for simplification and a decrease in cost of devices, and there is a problem that providing of a detecting mechanism such as a sensor does not accord with the needs.